Nucleic acid (NA)-based therapies using miRNAs (miRs) and/or anti-miRNA are being developed to promote or inhibit gene expression. miRNAs are non-coding RNAs that can regulate expression of networks of genes by the mechanism of RNA interference (RNAi). This occurs by incorporation of miRNA into an RNA-induced silencing complex (RISC) that mediate translational repression and degradation of target mRNAs. An antimiR is an oligonucleotide that is complementary to a miRNA that inhibits its function thereby de-represses the target genes of the miRNA. As mutations in genes and changes in miRNA profile are believed to be the underlying cause of cancer and other diseases, NA-based agents can directly act upon the underlying etiology, maximizing therapeutic potential. Non-limiting examples of NA-based therapies include: plasmid DNA (pDNA), small interfering RNA (siRNA), small hairpin RNA (shRNA), miR mimic (mimetic), anti-miR/antagomiR/miR inhibitor, and antisense oligonucleotide (ASO). Until the development of the nanoparticle compositions described herein, the clinical translation of NA-based therapies faced several obstacles in their implementation since transporting NAs to their intracellular target was particularly challenging and since NAs are relatively unstable and subject to degradation by serum and cellular nucleases. Further, the high negative charges of NAs made it impossible for diffusion across the cell membrane, further limiting utility.
A liposome is a vesicle composed of one or more lipid bilayers, capable of carrying hydrophilic molecules within an aqueous core or hydrophobic molecules within its lipid bilayer(s). As used herein, “lipid nanoparticles” is a general term to described lipid-based particles in the submicron range. Lipid nanoparticles can have structural characteristics of liposomes and/or have alternative non-bilayer types of structures. Drug delivery by lipid nanoparticles via systemic route requires overcoming several physiological barriers. The reticuloendothelial system (RES) is responsible for clearance of lipid nanoparticles from the circulation. Once escaping the vasculature and reaching the target cell, lipid nanoparticles are typically taken up by endocytosis and must release the drug into the cytoplasm prior to degradation within acidic endosomes and lysosomes.
In particular, the delivery of such nucleic acids (NAs), including siRNA and other therapeutic oligonucleotides is a major technical challenge that has limited their potential for clinical translation.
The development of efficient delivery vehicles is a key to clinical translation of oligonucleotide (ON) therapeutics. It is desired that a lipid nanoparticle formulation should be able to (1) protect the drug from enzymatic degradation; (2) transverse the capillary endothelium; (3) specifically reach the target cell type without causing excessive immunoactivation or off-target cytotoxicity; (4) promote endocytosis and endosomal release; and (5) form a stable formulation with colloidal stability and long shelf-life.